Appliance cord-connecting structure

ABSTRACT

The invention discloses a cord-connecting structure for stress relief beyond an appliance envelope using the usual elongated flexible bushing around the cord and anchored to the appliance to prevent sharp cord bends at the appliance. The bushing may have different internal cross sections to conveniently accommodate in part of its length twisted and preferably separated conductors and, in the rest of its length, to help rotationally restrain the cord by the bushing itself or equivalent. Thus, constant flexing of the cord, even with the tough new materials, imposes substantially no or very minimal stresses on the conductors throughout resulting in extremely long life and safer cords.

. United States Patent Denton [451 May 23, 1972 C -CO C NG FOREIGNPATENTS 0R APPLICATIONS 383,839 ll/l932 Great Britain ..339/l0l [72]Inventor: Bryce A. Denton, Ontario, Calif. 885,718 6/1943 France..339/l0$ 731 Assignee: General Electric Company PrimaryExanu'ner-Rtchard E. Moore [2 l May 1 1970 Attorney-lawreme R. Kempton,John F. Cullen, Leonard J. [21 1 AppL No: J89 Platt, Frank L. Neuhauserand Oscar B. Waddell Related US. Applicatlon Data [57 ABSTRACTContinuation-impart 0f The invention disclosesacord-connecting structurefor stress a 9 aballdonedrelief beyond an appliance envelope using theusual elongated flexible bushing around the cord and anchored to the ap-(g1. ufiaitulaaalgilgssfillgg puma to prevent sham cord bends at theapp|iance The [58] ,n i ""s' 'g 8 103 bushing may have differentinternal cross sections to con- "f veniently accommodate in part of itslength twist d and 56] Rderences cued preferably separated conductolsand, in the rest of its length, to help rotationally restrain the cordby the bushing itself or I UNITED STATES PATENTS equivalent. Thus,constant flexing of the cord, even with the 2,106,248 1/1938 Hedlund..339/101 x new subsanfiany my minimal stresses on the conductorsthroughout resulting in extremely long life and safer cords.

11 Claims, 5 Drawing Figures Patented May 23, 1972 3,665,374

Egg/ca A. Dania/ APPLIANCE CORD-CONNECTING STRUCTURE This is acontinuation-in-part of application Ser. No. 886,058 filed'Dec. l8,l969,now abandoned.

BACKGROUND OF THE INVENTION operated as opposed to the battery type.Thecords are of variv ous materials and, depending on the particularappliance, differentamounts of flexing of the cords occur in use. Intime, this wears the cord to expose the internal conductors or to breakthem, both resulting inpotentially dangerous shorts. Additionally, somehousehold appliances,-such as irons, can subject the cords to hightemperatures and consequent burning or charting again setting up apotential danger. Further, it is undesirable to transmit. stressor pullfrom a flexing cord to the appliance terminals for obvious reasons. Toovercome this, it is common to provide various forms of strain reliefsuch as knots, clamps, or plates within the appliance topermit slack inthe conductors between the appliance exit and the terminals to relievestress on the terminals; Additionally, in electrical appliances, variousparameters must be met to qualify for Underwriter Laboratory approval.While it is desired that the cord last the life of the appliance, it isfurther desirable that the cord be easily replaceable by the owner andstill be as safe as the original equipment. While such cords andrequirements vary, depending on the appliance, a typical appliance thatsubjects the cord to stringent conditions is the electric flatiron andit is to this appliance that the invention is directed although by nomeans so limited. Traditionally, the cord for supplying current to theheating element of a flatiron has been constructed in a manner known inthe industry as heater parallel twisted conductors or better known asI-IPD heater cord. Essentially, the construction consists of twomulti-strand conductors each overlaid with cotton thread followed byuncured rubber and then asbestos fiber. The conductors are twistedtogether and overlaid with a braided cotton outer layer. This approvedcord is flexible, long lived, and slides easily over the material beingironed without marking the cloth and the end connected to the terminalsinside the iron withstands the high temperatures involved. The cord doeshave some disadvantages. If, through negligence, the hot soleplatecontacts the outer braid for a short time, the braid is scorched andweakened so that it ultimately breaks exposing the asbestos and uncuredrubber to eventually expose the conductors with consequent danger.Failure may occur from constant cord flexing in using the iron withresultant chaffing of the insulation between the two conductors so thatthe insulation abrades allowing the two conductors to touch oneanotherand are between the conductors.

A later development of parallel conductor cord as used on appliances isa heater parallel neoprene or better known as HPN heater cord andthisconsists of two multi-strand conductors, each coated with tin orcovered with a layer of material such as cotton thread or paper ribbonwhich are then coated with an insulating material such as neoprenerubber by extrusion of the rubber and conductors through a die while theconductors are separated so the extruded rubber holds the conductorsapart and acts as an insulation between them and provides an outercovering. A'flat extrusion may include a connecting web, like thewell-knownlamp cord, so that conductors are easily rippable to separatethem for connection to the terminals. Neoprene covered HPN heater cordhas not been cloth as it is pulled across it during ironing. A recentmaterial that is an improvement on neoprene is chlorosulphonatedpolyethylene such as is available under the name l-iypalon." This hasthe advantage of sliding easily over the cloth and it does not mark thecloth. Also, it has the extremely tough coating as well as being moreresistant to high temperatures than neoprene. Consequently, a hot ironcan be placed on such a cord for several minutes without damaging it.Because of the toughness of this particular polyethylene material, ifconductors fail from constant flexing they simply open circuit with noarcing because the fine multi-strand conductors cannot penetrate thecoating.

Tests of such cords on irons, however, have shown several earlyfailures. It appears that the failures are the result of the parallelconductor cord being quite flexible over'its short axis but not flexiblein the direction of its long axis. Consequently, when it is forceablyflexed over its long axis, as occurs during movement of an iron, oneconductor, including its individual strands, is in tension and the otheris in compression. The many strands of the conductor under compressiontend to mushroom" within the wire coating or tube resulting in a sharpbend and they break causing an open circuit failure. They cannotpenetrate the tough coating to cause a direct short and arcing but theiron is out of commission. In any appliance, these failures will occurat the point-where the flexing is greatest. In the flatiron, thisusually occurs just above the point where the cord is tightly compressedbetween two parts generally in the iron handle. The compressing orclamping is one conventional strain relief to prevent any pull on thecord being transmitted to the terminals. Generally, the cord exits fromthe iron just above this strain relief through a protective bushing toprevent sharp cord bends and it is this point that is constantly flexedto put the individual wires under the constantly changingtension-compression stresses and eventual breakage. Inability to correctthis defect has prevented the use of the improved tougher and moreheat-resistant rubber.

SUMMARY OF THE INVENTION Briefly described, the invention is directed toan appliance, such as a flatiron, that has an electric cord secured toterminals within the iron by a portion of the cord that has separatedconductors to conduct electric power to the iron. In this appliance, animprovement is provided in the cord-iron connection that uses anelongated flexible sleeve bushing sur' rounding the cord and anchored tothe iron at one end to prevent sharp cord bends at the iron. The cordmay be any shape but is conveniently a flat two-wire parallel cord and,in one of the new materials, has a molded chlorosulphonated polyethylenecovering over the conductors which is formed to rippably separate theconductors. The flexible bushing preferably has lengths of differentinternal cross sections around the cord. The separated conductor portionof the cord that'connects to the terminals may be continued to extendoutside the iron envelope into a selected length of the bushing whichlength has an internal cross section larger than the cord or anunseparated portion may extend into the bushing. When separated, eachseparated conductor is twisted lengthwise at least partially around itsadjacent conductor and the twisted conductors are held twisted and aredisposed in the bushing length that has the larger cross section. Ifunseparated, the cord is turned to twist the conductors at leastone-quarter twist or in the bushing length. The remainder of the bushinglength may have an internal cross section that conforms to the crosssection of the unripped cord, such as the flat cord, and rotationallyrestrains the cordor separate means may prevent the cord fromuntwisting. A strain relief means for compressing the conductors betweenthe terminals and the twisted conductors is provided. With this improvedconnection structure, very minimum or substantially no stress is imposedon the conductors at the terminals or in the bushing during continuousflexing. Thus, the main object is to provide an improved cord-applianceconnection that substantially prevents any stress on the conductors andwhich provides long life under constant flexing even when using thetough high temperature coatings available.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial cross-sectionalview of the preferred improved cord connection structure as used on anappliance DESCRIPTION OF THE PREFERRED EMBODIMENT The .invention -isapplicable to any cord-connected appliance but is specificallyapplicable to an electric flatiron and will be described in connectiontherewith. Also it is applicable to any cord using plural conductorssuch as those using a grounding conductor or the more common dualconductor cord and the invention is described in connection with thelatter but is not so limited as will be apparent.

Referring first to FIG. 1, there is shown an electric flatiron handlefrom which the usual cord 12 extends. As shown, the cord extends out ofthe top of the handle at the rear thereof for convenient use by arightor left-handed operator although it can extend from the sides in awell-known manner and the invention is applicable to any suchconnection. After entering the handle, to connect to the iron, the cordhas a portion generally separated into plural such as two conductors l4and 16 and the individual conductors are connected to terminals l8. Toprevent any strain from pulling on the cord being transmitted to theterminals 18, it is customary to prothat any amount of flexing does notbreak the individual wires. To this end, the preferred form of theinvention provides a formed bushing 24 with different internal crosssections to neutralize the tension and compression stresses. As shown,bushing 24 is provided with a selected length 28 of generally oneinternal cross section that, as shown in FIG. 1, practically is largerthan the cross section of cord 12 to form an enlarged cavity. Theremaining length 30 of the busing is formed to have a length that has across section conforming to the cross section of the cord regardless ofthe cord shape.

It has been found that breakage due to flexing can be minimized orsubstantially eliminated by twisting the conductors and holding themtwisted within the bushing. This may be accomplished either by windingor turning the entire cord lengthwise at least one-quarter turn or 90 asshown at the top of FIG. 1 but putting the twist entirely within thebushing or by rippably separating the two conductors and twisting themaround one another at least 90 within the bushing as shown at 28 andholding the cord to prevent unwinding. Practically, the latter ispreferred and it is in this manner that the invention will be describedas the best mode although it will be appreciated that separating theconductors is not absolutely essential, merely that the conductors betwisted and held.

To neutralize the compression and tension stresses of the individualwires, the separated conductors are extended back a sufiicient distanceto permit each conductor to be twisted lengthwise within the largerbushing cross section as shown in FIG. 1 and mostly outside the ironenvelope. This twisting is a vide a strain relief means of some form.Typically, such a relief as shown at 39 in U.S. Pat. No. 2,727,322 or astrain relief 4 plate as shown at 74 in U.S. Pat. No. 2,602,248 both ofcommon assignment. It is common in such irons to provide an elongatedflexible sleeve bushing 24 that surrounds the cord and is anchored tothe iron at one end by means, such as formed lips 26, better seen inFIG. 2 that engage under a matching overhead in the handle. The bushingextends out sufficiently far to prevent any sharp cord bends at the ironand the strain relief means acting on the conductors is generallydisposed between the anchor and terminals all as well-known in the art.

The use of the newer improved materials, such as chlorosulphonatedpolyethylene or other materials with similar characteristics, which areextruded directly over the conductors and formed to be rippable, haspresented problems because of the constant flexing required in an iron.In parallel conductor cords, whether round, or of the better known flatwire type, it will be apparent that the cord is flexible over its shortaxis x -x meaning that it bends quite easily across its narrow dimensionas shown in FIG. 2 but-it is much more inflexible to bending about itsright angle axis y-y or wide dimension. Bending about y-y strains theindividual wires putting them under tension and compression with thecompression mushrooming the wires and breaking them. Fortunately,because of the toughness of the molded cord covering, any breakage thatdoes occur in the wires from this action results only in an open circuitsince the wires cannot penetrate the covering, however, the appliance isout of commission. Thus, it is necessary to remove the tension andcompression that occur in the individual wires of the conductors soseparated or rippable cord conductors, when twisted, occupy morecross-sectional area than the untwisted portion, the cavity over theselected length 28 is made to accommodate the twisted conductors. Itwill be seen that the twisting of the conductors whether separated ornot places a given wire within the conductor under alternate tension andcompression whereby the twisting effectively cancels or neutralizes thestresses so the individual wires are not stressed. Technically, it isimpossible to bend without stress that, in time, e.g., a million cycles,could take a toll. However, within a long product lifetime, any stressis completely minimal and there is practically no stress and this iswhat is intended as used herein. Consequently, the cord may be flexed inany direction without placing the individual wires of the conductorsunder any stress. As shown in FIG. 4, the selected length 28 may beconveniently formed round although any size or shape will suffice thataccommodates the twisted conductors and, in the preferred embodiment asshown, this, as a practical matter, results in a larger cross sectionover the selected length although a molded cavity to accommodate thetwisted conductors could be formed. The remaining length 30 of bushing26 is made to have an internal cross section that conforms to the wirecross section as shown in FIG. 3. It is merely necessary that this crosssection in the bushing conform to the unripped parallel conductor cordso that it provides a length and thus a means connected to the cord thatboth prevents the twisted section from becoming untwisted androtationally restrains the cord therein by pressing against the widedimensions or effectively on the parallel conductors, for example,lamp-type or non-round cord would be pressed on the wide portion toprevent turning. When using a substantially flat cross section 30 asshown, the cord, as it exits from bushing 26, which can be of the sametough material, inherently tends to bend about its flexible axis x-x asshown in FIG. 2, but since this is over a long radius no stresses orstrains are put on the individual wires and no breakage occurs at thispoint. Similarly, any other cross section naturally permits the cord toassume its flexible bending position about its x-x axis or narrowestdimensionbeyond the bushing and no stress is applieding length 30 actingin conjunction with the selected length 28 to prevent turning and holdthe twisted portion of the conductors therein, there is no destructivestress applied to the individual conductors due to any bending about theinflexible axis y--y back in the bushing-The parts are easily assembledby passing the cord through the bushing from the anchor end and pullingthe twisted portion into the bushing. Also, this assembly may be sold asan easily-installed replacement.

To ensure the minimum 90 twist in assembly, the bushing can be molded torequire the twist such as by making length 30 at 90 to the lay of thecord as it comes from terminals 18. This merely means that the sectionshown in FIG. 3 would be rotated 90 so that the oblong opening shown as30 would be vertical and the function is identical. However, this is anmanufacturing assembly precaution and is not really necessary. Further,while portion 30 is preferred it will be apparent that, once assembled,tongue 22 effectively connects on the cord to prevent untwisting in thebushing of the separated conductors when the tough material is used andportion 30 may merely serve as a filler" so the cord exit from thebushing is esthetically pleasing.

As shown in FIG. 5 an alternate form may be used to restrain the cordfrom untwisting when the conductors are separated if bushing portion 30is not relied on. This form is desirable when the cord is supplied as areplacement cord to ensure that it is properly twisted when installed.To this end the cord 12 is turned and separated over a given length asin FIG 1 into two conductors that are then twisted lengthwise a minimumof 90 and preferably once around the adjacent conductor as seen in FIG.5. The separated conductors are held in the twisted position by anysuitable clamping means 32 that is connected to the cord as by pinchingaround the conductors. This assembly may be placed in a bushing likethat of FIG. 2 whereupon cavity 28 may even be substantially the fulllength of the bushing, i.e., selected length portion 30 may be shortermerely to act as a filler or close the end at the cord exit for goodappearance. The primary restraining force against rotation in thebushing is by clamp 32. Also, the assembly may be sold as a replacementcord that can only be installed properly since it has a fixed twistbecause of the clamp.

The use of the elongated bushing with the two internal cross sectionsproviding a pressing and rotationally restraining action in thecombination with the twisted cord portion or the twisted conductors withthe separate restraining clamp means both with the normal strain reliefmeans thus results in complete cord flexibility in all directions.Especially when used with the tough impenetrable rubber that preventsarcing, the improvement results in a durable long life cord thatoutlasts a standard cord'with no danger of short circuiting.

While there have been described preferred forms of the invention,obvious equivalent variations are possible in light of the aboveteachings. It is therefore to be understood that within the scope of theappended claims the invention may be practised, otherwise than asspecifically described, and the claims are intended to cover suchequivalent variations.

1 claim:

1. In a portable appliance with an electric cord connected to terminalswithin the appliance by a portion of the cord having separatedconductors to conduct power to the appliance, the improvement in thecord-appliance connection comprising;

an elongated flexible sleeve bushing surrounding said cord and anchoredto the appliance preventing sharp cord bends at the appliance,

said cord extending into a selected length of the bushing and beingturned to provide twisted conductors therein at least lengthwise,

strain relief means between the bushing anchor and terminals acting onthe conductors, a cavity in said bushing over said selected length toaccommodate the twisted conductors, and means rotationally restrainingsaid conductors from untwisting, whereby minimal stress is imposed onsaid conductors at said terminals or at said bushing during flexing.

2. Apparatus as described in claim 1 wherein the rotationallyrestraining connecting means is disposed within said bushing.

3. Apparatus as described in claim 1 wherein said bushing has a lengthbeyond said selected length with an opening therethrough confonning tothe cross section of and rotationally restraining said cord.

4. Apparatus as described in claim 3 wherein said cord is a parallelnon-round conductor cord with the cross section pressing on saidparallel conductors and said separated conductor portion extends intosaid selected bushing length.

5. Apparatus as described inv claim 1 wherein the cord covering oversaid conductors is a chlorosulphonated polyethylene that is molded oversaid conductors and is formed to rippably separate said conductors.

6. Apparatus as described in claim 4 wherein the cord is a flat wirecord flexible to bending across its narrow dimension and resistantacross its wide dimension.

7. In a flatiron with an electric cord secured to terminals within theiron by a portion of the cord having separated conductors to conductpower to the iron, the improvement in the cord-iron connectioncomprising;

an elongated flexible sleeve bushing surrounding said cord and anchoredto the iron at one end thereof preventing sharp cord bends at the iron,

said bushing having lengths of different internal cross sections aboutsaid cord,

said separated conductor portion of said cord extending into a selectedlength of said bushing having an internal cross section larger than saidcord,

each conductor being twisted lengthwise at least 90 lengthwise aroundthe adjacent conductor,

means between the twisted conductors and terminals to compress theseparated conductors against the iron, the twisted conductors beingdisposed in said selected bushing length,

the remainder of said bushing length having an internal cross sectionconforming to the cross section of and rotationally restraining saidcord,

whereby no stress is imposed on said conductors at said terminals or insaid bushing during flexing.

8. Apparatus as described in claim 7 wherein said cord is a parallelnon-round conductor cord with the bushing cross section pressing on saidparallel conductors.

9. Apparatus as described in claim 7 wherein the cord covering over saidconductors is a chlorosulphonated polyethylene that is molded over saidconductors and is formed to rippably separate said conductors.

10. Apparatus as described in claim 8 wherein the cord is a flat wirecord flexible to bending across its narrow dimension and resistantacross its wide dimension.

11. Apparatus as described in claim 10 wherein said internal crosssection adjacent said bushing anchor is substantially round and theremaining internal bushing cross section under 7 said pressed crosssection is substantially flat.

1. In a portable appliance with an electric cord connected to terminalswithin the appliance by a portion of the cord having separatedconductors to conduct power to the appliance, the improvement in thecord-appliance connection comprising; an elongated flexible sleevebushing surrounding said cord and anchored to the appliance preventingsharp cord bends at the appliance, said cord extending into a selectedlength of the bushing and being turned to provide twisted conductorstherein at least 90* lengthwise, strain relief means between the bushinganchor and terminals acting on the conductors, a cavity in said bushingover said selected length to accommodate the twisted conductors, andmeans rotationally restraining said conductors from untwisting, wherebyminimal stress is imposed on said conductors at said terminals or atsaid bushing during flexing.
 2. Apparatus as described in claim 1wherein the rotationally restraining connecting means is disposed withinsaid bushing.
 3. Apparatus as described in claim 1 wherein said bushinghas a length beyond said selected length with an opening therethroughconforming to the cross section of and rotationally restraining saidcord.
 4. Apparatus as described in claim 3 wherein said cord is aparallel non-round conductor cord with the cross section pressing onsaid parallel conductors and said separated conductor portion extendsinto said selected bushing length.
 5. Apparatus as described in claim 1wherein the cord covering over said conductors is a chlorosulphonatedpolyethylene that is molded over said conductors and is formed torippably separate said conductors.
 6. Apparatus as described in claim 4wherein the cord is a flat wire cord flexible to bending across itsnarrow dimension and resistant across its wide dimension.
 7. In aflatiron with an electric cord secured to terminals within the iron by aportion of the cord having separated conductors to conduct power to theiron, the improvement in the cord-iron connection comprising; anelongated flexible sleeve bushing surrounding said cord and anchored tothe iron at one end thereof preventing sharp cord bends at the iron,said bushing having lengths of different internal cross sections aboutsaid cord, said separated conductor portion of said cord extending intoa selected lengTh of said bushing having an internal cross sectionlarger than said cord, each conductor being twisted lengthwise at least90* lengthwise around the adjacent conductor, means between the twistedconductors and terminals to compress the separated conductors againstthe iron, the twisted conductors being disposed in said selected bushinglength, the remainder of said bushing length having an internal crosssection conforming to the cross section of and rotationally restrainingsaid cord, whereby no stress is imposed on said conductors at saidterminals or in said bushing during flexing.
 8. Apparatus as describedin claim 7 wherein said cord is a parallel non-round conductor cord withthe bushing cross section pressing on said parallel conductors. 9.Apparatus as described in claim 7 wherein the cord covering over saidconductors is a chlorosulphonated polyethylene that is molded over saidconductors and is formed to rippably separate said conductors. 10.Apparatus as described in claim 8 wherein the cord is a flat wire cordflexible to bending across its narrow dimension and resistant across itswide dimension.
 11. Apparatus as described in claim 10 wherein saidinternal cross section adjacent said bushing anchor is substantiallyround and the remaining internal bushing cross section under saidpressed cross section is substantially flat.